Purpose:The purpose of this study was to examine effects of a sport version of a semi-rigid ankle brace (ElementTM) and a soft ankle brace (ASO) on ankle biomechanics and ground reaction forces (GRFs) during a drop la...Purpose:The purpose of this study was to examine effects of a sport version of a semi-rigid ankle brace (ElementTM) and a soft ankle brace (ASO) on ankle biomechanics and ground reaction forces (GRFs) during a drop landing activity in subjects with chronic ankle instability (CAI)compared to healthy subjects with no history of CAI.Methods:Ten healthy subjects and 10 subjects who had multiple ankle sprains participated in the study as the control and unstable subjects,respectively.The CAI subjects were age,body mass index and gender matched with the control subjects.The arch index and ankle functions of the subjects were measured in a subject screening session.During the biomechanical test session,participants performed five trials of drop landing from 0.6 m,wearing no brace ( NB),ElementTM brace and ASO brace.Simultaneous recording of three-dimensional kinematic (240 Hz)and GRF (1200 Hz) data were performed.Results:The CAI subjects had lower ankle functional survey scores.The arch index and deformity results showed greater arch deformity of ElementTM against a static load than in NB and ASO due to greater initial arch position held by the brace.CAI participants had greater eversion velocity than healthy coutrols.The ASO brace reduced the first peak vertical GRF whereas ElementTM increased 2nd peak vertical GRF.ElementTM brace reduced eversion range of motion (ROM) and peak eversion velocity compared to NB and ASO.In addition,ElementTM reduced dorsiflexion ROM and increased peak plantarflexion moment compared to NB and ASO.Conclusion:Results of static arch measurements and dynamic ankle motion suggest that the restrictions offered by both braces are in part due to more dorsiflexed ankle positions at contact,and higher initial arch position and stiffer ankle for ElementTM.展开更多
The versatile motion capability of snake robots offers themselves robust adaptability in varieties of challenging environments where traditional robots may be incapacitated.This study reports a novel flexible snake ro...The versatile motion capability of snake robots offers themselves robust adaptability in varieties of challenging environments where traditional robots may be incapacitated.This study reports a novel flexible snake robot featuring a rigid-flexible coupling structure and multiple motion gaits.To better understand the robot's behavior,a bending model for the soft actuator is established.Furthermore,a dynamic model is developed to map the relationship between the input air pressure and joint torque,which is the model base for controlling the robot effectively.Based on the wave motion generated by the joint coupling direction function in different planes,multiple motion gait planning methods of the snake-like robot are proposed.In order to evaluate the adaptability and maneuverability of the developed snake robot,extensive experiments were conducted in complex environments.The results demonstrate the robot's effectiveness in navigating through intricate settings,underscoring its potential for applications in various fields.展开更多
Continuously increasing applications of robot technologies in unstructured environments put higher requirements on the robotic grippers'performance,such as interaction capability,output force range,and controllabi...Continuously increasing applications of robot technologies in unstructured environments put higher requirements on the robotic grippers'performance,such as interaction capability,output force range,and controllability.However,currently,it is hard for either rigid or soft grippers to meet these requirements,as single soft or rigid structures alone are difficult to effectively overcome/alleviate their inherent defects,e.g.,low compliance of rigid structures and low output force of soft structures.To deal with these difficulties,soft-rigid coupling grippers,or hybrid grippers are proposed.Technically,the soft-rigid coupling is a promising design that combines soft and rigid structures,in order to exploit their respective advantages,such as the strength of rigid structures and compliance of soft structures,in the same set of the gripper system.For the first time,herein,this paper systematically discusses the collaboration strategies of the existing hybrid robotic grippers,by classifying them as Rigid-activesoft-passive,Rigid-passive-soft-active,and Rigid-active-soft-active.At the same time,we introduce the integrated fabrication methods of hybrid grippers,through which the soft and rigid structures with great stiffness and property differences can be coupled together to construct a stable system.Also,possible performance improvements on soft-rigid coupling design for gripper systems are discussed.展开更多
Soft in-pipe robot has good adaptability in tubular circumstances,while its rigidity is insufficient,which affects the traction performance.This paper proposes a novel worm-like in-pipe robot with a rigid and soft str...Soft in-pipe robot has good adaptability in tubular circumstances,while its rigidity is insufficient,which affects the traction performance.This paper proposes a novel worm-like in-pipe robot with a rigid and soft structure,which not only has strong traction ability but also flexible mobility in the shaped pipes.Imitating the structure features of the earthworm,the bionic in-pipe robot structure is designed including two soft anchor parts and one rigid telescopic part.The soft-supporting mechanism is the key factor for the in-pipe robot excellent performance,whose mathematical model is established and the mechanical characteristics are analyzed,which is used to optimize the structural parameters.The prototype is developed and the motion control strategy is planned.Various performances of the in-pipe robot are tested,such as the traction ability,moving velocity and adaptability.For comparative analysis,different operating scenarios are built including the horizontal pipe,the inclined pipe,the vertical pipe and other unstructured pipes.The experiment results show that the in-pipe robot is suitable for many kinds of pipe applications,the average traction is about 6.8N,the moving velocity is in the range of 9.5 to 12.7 mm/s.展开更多
We investigated the macro-and micro-mechanical properties of rigid-grain and soft-chip mixtures(GCMs)through numerical simulations using the discrete element method.We present a novel framework for the discrete modeli...We investigated the macro-and micro-mechanical properties of rigid-grain and soft-chip mixtures(GCMs)through numerical simulations using the discrete element method.We present a novel framework for the discrete modeling of soft chips and rigid grains in conjunction with calibration processes.Several numerical triaxial tests were also performed on GCMs with 0%,10%,20%,and 30%volumetric chip contents,P.The simulation results demonstrate that increasing P leads to higher GCM toughness,higher deviatoric peak stress,and higher corresponding shear strain.Higher P also contributes to more volume contraction and less dilation.The friction angles at both the peak and residual state significantly increase with increasing P.In view of the micro-mechanical features,strong contact force chains develop along the loading direction,which results in considerable anisotropy in the peak and residual states.Both the formation of strong force chains and rotation of grains decrease with increasing P,whereas the grain sliding percentage increases.The tensile force is mobilized with shearing and higher P leads to less mobilization of the tensile force.These findings are useful for better understanding the internal structure of GCMs with different soft-chip contents,especially in granular mixture mechanics and geomechanics.展开更多
基金supported in part by DeRoyal Industries, Inc.,Powell,TN,USA
文摘Purpose:The purpose of this study was to examine effects of a sport version of a semi-rigid ankle brace (ElementTM) and a soft ankle brace (ASO) on ankle biomechanics and ground reaction forces (GRFs) during a drop landing activity in subjects with chronic ankle instability (CAI)compared to healthy subjects with no history of CAI.Methods:Ten healthy subjects and 10 subjects who had multiple ankle sprains participated in the study as the control and unstable subjects,respectively.The CAI subjects were age,body mass index and gender matched with the control subjects.The arch index and ankle functions of the subjects were measured in a subject screening session.During the biomechanical test session,participants performed five trials of drop landing from 0.6 m,wearing no brace ( NB),ElementTM brace and ASO brace.Simultaneous recording of three-dimensional kinematic (240 Hz)and GRF (1200 Hz) data were performed.Results:The CAI subjects had lower ankle functional survey scores.The arch index and deformity results showed greater arch deformity of ElementTM against a static load than in NB and ASO due to greater initial arch position held by the brace.CAI participants had greater eversion velocity than healthy coutrols.The ASO brace reduced the first peak vertical GRF whereas ElementTM increased 2nd peak vertical GRF.ElementTM brace reduced eversion range of motion (ROM) and peak eversion velocity compared to NB and ASO.In addition,ElementTM reduced dorsiflexion ROM and increased peak plantarflexion moment compared to NB and ASO.Conclusion:Results of static arch measurements and dynamic ankle motion suggest that the restrictions offered by both braces are in part due to more dorsiflexed ankle positions at contact,and higher initial arch position and stiffer ankle for ElementTM.
基金financially supported by the Joint Fund of National Natural Science Foundation of China with Shenzhen City(U2013212)the National Key R&D Program of China(2020YFB1313001).
文摘The versatile motion capability of snake robots offers themselves robust adaptability in varieties of challenging environments where traditional robots may be incapacitated.This study reports a novel flexible snake robot featuring a rigid-flexible coupling structure and multiple motion gaits.To better understand the robot's behavior,a bending model for the soft actuator is established.Furthermore,a dynamic model is developed to map the relationship between the input air pressure and joint torque,which is the model base for controlling the robot effectively.Based on the wave motion generated by the joint coupling direction function in different planes,multiple motion gait planning methods of the snake-like robot are proposed.In order to evaluate the adaptability and maneuverability of the developed snake robot,extensive experiments were conducted in complex environments.The results demonstrate the robot's effectiveness in navigating through intricate settings,underscoring its potential for applications in various fields.
基金supported by the National Natural Science Foundation of China(Grant Nos.52188102 and U1613204)。
文摘Continuously increasing applications of robot technologies in unstructured environments put higher requirements on the robotic grippers'performance,such as interaction capability,output force range,and controllability.However,currently,it is hard for either rigid or soft grippers to meet these requirements,as single soft or rigid structures alone are difficult to effectively overcome/alleviate their inherent defects,e.g.,low compliance of rigid structures and low output force of soft structures.To deal with these difficulties,soft-rigid coupling grippers,or hybrid grippers are proposed.Technically,the soft-rigid coupling is a promising design that combines soft and rigid structures,in order to exploit their respective advantages,such as the strength of rigid structures and compliance of soft structures,in the same set of the gripper system.For the first time,herein,this paper systematically discusses the collaboration strategies of the existing hybrid robotic grippers,by classifying them as Rigid-activesoft-passive,Rigid-passive-soft-active,and Rigid-active-soft-active.At the same time,we introduce the integrated fabrication methods of hybrid grippers,through which the soft and rigid structures with great stiffness and property differences can be coupled together to construct a stable system.Also,possible performance improvements on soft-rigid coupling design for gripper systems are discussed.
基金National Natural Science Foundation of China,52005369Open Project Fund of Tianjin Key Laboratory of Integrated Design and Online Monitoring of Light Industry and Food Engineering Machinery and Equipment,2020LIMFE05.
文摘Soft in-pipe robot has good adaptability in tubular circumstances,while its rigidity is insufficient,which affects the traction performance.This paper proposes a novel worm-like in-pipe robot with a rigid and soft structure,which not only has strong traction ability but also flexible mobility in the shaped pipes.Imitating the structure features of the earthworm,the bionic in-pipe robot structure is designed including two soft anchor parts and one rigid telescopic part.The soft-supporting mechanism is the key factor for the in-pipe robot excellent performance,whose mathematical model is established and the mechanical characteristics are analyzed,which is used to optimize the structural parameters.The prototype is developed and the motion control strategy is planned.Various performances of the in-pipe robot are tested,such as the traction ability,moving velocity and adaptability.For comparative analysis,different operating scenarios are built including the horizontal pipe,the inclined pipe,the vertical pipe and other unstructured pipes.The experiment results show that the in-pipe robot is suitable for many kinds of pipe applications,the average traction is about 6.8N,the moving velocity is in the range of 9.5 to 12.7 mm/s.
基金This research was supported by the Doctoral Fund of Central South University(grant number 1053320170862)National Nat-ural Science Foundation of China(grant number 51678575)+1 种基金the Science Foundation of CARS(grant number 2019YJ026)The authors express their appreciation for the financial assistance.
文摘We investigated the macro-and micro-mechanical properties of rigid-grain and soft-chip mixtures(GCMs)through numerical simulations using the discrete element method.We present a novel framework for the discrete modeling of soft chips and rigid grains in conjunction with calibration processes.Several numerical triaxial tests were also performed on GCMs with 0%,10%,20%,and 30%volumetric chip contents,P.The simulation results demonstrate that increasing P leads to higher GCM toughness,higher deviatoric peak stress,and higher corresponding shear strain.Higher P also contributes to more volume contraction and less dilation.The friction angles at both the peak and residual state significantly increase with increasing P.In view of the micro-mechanical features,strong contact force chains develop along the loading direction,which results in considerable anisotropy in the peak and residual states.Both the formation of strong force chains and rotation of grains decrease with increasing P,whereas the grain sliding percentage increases.The tensile force is mobilized with shearing and higher P leads to less mobilization of the tensile force.These findings are useful for better understanding the internal structure of GCMs with different soft-chip contents,especially in granular mixture mechanics and geomechanics.
